tablet – How root android 8.1 gtaxlwifi?

i wanna root my tablet, Samsung Galaxy Tab A. I tried enable bootloader using Adb & fastboot and later twrp and magisk, but i couldnt use Fastboot Commands, even with drivers. So, are there way to unlock bootloader with/without pc?

Note:
I am using Ubuntu at pc

I will be thankfull if u say method :]